[PATCH 06/13] sysfs: simplify sysfs_kf_seq_show

Christoph Hellwig
2021-09-13T05:48:35Z

Contrary to the comment ->show is never called from lseek for sysfs,
given that sysfs does not use seq_lseek. So remove the NULL ->show
case and just WARN and return an error if some future code path ends
up here.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/sysfs/file.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 74a2a8021c8bb..42dcf96881b68 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -45,6 +45,9 @@ static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
ssize_t count;
char *buf;

+ if (WARN_ON_ONCE(!ops->show))
+ return -EINVAL;
+
/* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
count = seq_get_buf(sf, &buf);
if (count < PAGE_SIZE) {
@@ -53,15 +56,9 @@ static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
}
memset(buf, 0, PAGE_SIZE);

- /*
- * Invoke show(). Control may reach here via seq file lseek even
- * if @ops->show() isn't implemented.
- */
- if (ops->show) {
- count = ops->show(kobj, of->kn->priv, buf);
- if (count < 0)
- return count;
- }
+ count = ops->show(kobj, of->kn->priv, buf);
+ if (count < 0)
+ return count;

/*
* The code works fine with PAGE_SIZE return but it's likely to
--
2.30.2